Energy and Matter in Cells

Sections

Engage: My, How I've Grown!

The title of this section is "My, How I've Grown!" Does it even seem possible that a big apple tree with lots of apples starts out as a tiny seed? Where did all that mass come from? In this resource we'll start by comparing the mass of an apple to the mass of an apple seed to see the difference.

Use the materials and equipment below to answer the question "What is the difference in mass of one apple seed and one apple?"Use a pencil and paper or your science journal to work through the calculations.

Now that you have found the difference in mass between an apple seed and an apple, think about this question: "Where did the mass of the apple come from?" Click to play the video below for more clues.

Explore: Carbon Dioxide Testing

We've used an indicator to test for the presence of CO2 as evidence of the breakdown of a larger molecule. Would you get the same results if you tested living organisms? Perform the virtual lab belowto answer the following question: "Do both plants and animals break down larger compounds from plant-based foods and release CO2?" Use the "Snails and Sprigs Virtual Lab Investigation" document as a reference to the lab procedures. You'll need paper and pen or your lab journal to record data and observations. A copy of the lab procedures is available in "Related Items" below.

Explain: What Goes Around, Comes Around

Source:

The TedEd video above was captured on YouTube 4/18/13.

Photosynthesis Equation 6CO2 + 6H2O → C6H12O6 + 6O2

Cellular Respiration Equation C6H12O6 + 6O2 → 6CO2 + 6H2O

Closely examine the equations above. What do you observe about them? Do they have anything in common? Are the chemical compounds in the reactants and products familiar to you?

They represent how matter and energy are produced and stored in plants and other photosynthetic organisms and how matter is broken down and energy released so that organisms can function.The equations also represent how matter cycles through the environment. In fact, photosynthesis and cellular respiration are important processes in the water, carbon, and oxygen cycles.

Look at the equations again, and this time pay attention to the number of atoms of each element in the compounds. Do you see a pattern? You can see the matter represented, but can you see the energy?The energy is trapped in the bonds that atoms form when compounds like glucose are created.To release the energy, the food has to break down. Go to the next section to find out how much energy can be stored in food.

Elaborate: Energy to Burn

Let's examine energy and matter in cells using calorimetry. Calorimetry is a way to measure energy transfer. In this investigation, we'll use calorimetry to find out how much energy is stored in a cashew.

In fact, there are several questions we can answer from data taken when performing the experiment. Here are the questions you'll need to answer:

– How much energy is stored in a cashew?

– How much energy is stored in 1 gram of the cashew?

– Does your data agree with the nutrition label?

– What is your percent error?

– What percentage of matter reentered the atmosphere?

Watch the first video to make observations and record data.

Source:

Picture of the nutrition label captured from http://caloriecount.about.com.